1. Field of the Invention
This invention relates generally to removal of buried objects from the ground. More specifically, this invention relates to surrounding buried waste of a given diameter with a larger diameter casing, sealing the bottom of the casing with grout, and pulling the sealed casing out of the ground with the grout plug intact to retrieve the buried waste.
2. Related Art
U.S. Pat. No. 5,980,446 (Loomis et al.) discloses a method for injecting grout underground to form solid columns. A series of the columns may be overlapped to surround and isolate, for example, a buried waste pit.
Prior to enactment of current environmental regulations, waste was buried that must now be retrieved and then sent to an appropriate treatment, storage, or disposal facility (TSD). Some of these wastes, because of high worker safety risks or significant potential for contamination spread, will be difficult to retrieve using normal excavation techniques. For instance, from 1954 to 1967, Hanford 300 Area transuranic and other wastes were disposed of in the 618-10 and 618-11 Burial Grounds. Much of these wastes were disposed of in what was referred to as a vertical pipe unit (VPU). VPUs were constructed by welding 5 open-ended 55-gal drums end to end. Constructed VPUs were positioned in trenches to form vertical shafts, and wastes were deposited in the shafts. When full, VPUs were backfilled, capped with concrete, and buried under four to six feet of clean soil. The waste in these VPUs is potentially highly radioactive and in a form such that traditional excavation using a loader or backhoe may cause undue risk to workers or the environment.